Nearly 3 lakh people fled their homes in coastal areas of Odisha and Andhra Pradesh on Friday as a massive cyclone - so large it filled nearly the entire Bay of Bengal - gathered strength and headed towards eastern coast, while army mobilised to assist in evacuation and rescue efforts.

Forecasters said cyclone Phailin, which will make landfall near Gopalpur in Odisha on Saturday evening, was a "very severe cyclonic storm" and is expected to cause large-scale power and communications outages and shut down rail links if it continues on its current path without weakening.

Within 24 hours, Cyclone Phailin went from a Category 1 storm to Category 4 (on a scale going up to 5), according to London-based storm-tracking system Tropical Storm Risk.

The warning brought back memories of a killer cyclone which left nearly 10,000 people dead in 1999 and caused widespread devastation whose effects are felt by the state even now.

Some forecasters likened its size and intensity to that of hurricane Katrina, which devastated the US Gulf coast and New Orleans in 2005.

This time, however, the state government sought to calm fears and said it was better prepared. Chief minister Naveen Patnaik appealed to people to stay calm and assist local administration in handling the crisis. "The government is fully prepared," Patnaik told reporters.

It broadcast cyclone warnings through loudspeakers and on radio and television as the first winds were felt on the coast and in the state capital, Bhubaneswar. Army and disaster management teams are on the standby to help in evacuation and rescue measures.

Union home secretary said nearly 12 million people will be affected by the cyclone.

Using trucks and buses, authorities evacuated more than 260,000 people from dozens of vulnerable villages in coastal Odisha and Andhra Pradesh to government-run shelters, schools and buildings. More than 1 lakh were evacuated from Odisha's Ganjam district ---the most vulnerable to Phailin’s landfall -- alone.

Andhra Pradesh chief minister N Kiran Kumar Reddy late on Friday night spoke to collectors of Srikakulam, Vizianagaram, Visakhapatnam and East Godavari districts to review the administration's preparedness, as a red alert has been sounded in view of the cyclone.

Odisha special relief commissioner Pradeep Kumar Mohapatra said about 5 lakh were expected to move to shelters in the state.

Besides 280 multi-purpose cyclone shelters in the vulnerable districts, about 10,000 concrete schools have been converted into temporary cyclone shelters to house the evacuated people. These shelters have been stocked with food items, medicines and auto fuels.

National Disaster Management Authority vice-chairman M Shashidhar Reddy said 23 NDRF teams were assisting local administrations and more were on standby. “Around 1.2 crore people are expected to be affected,” he said, adding that parts of Chhattisgarh, Jharkhand, Uttar Pradesh, Bihar and West Bengal could also be hit.

The Centre has constituted 30 quick response medical teams to be moved in at short notice.

Members of NDRAF arrive at Bhubaneswar airport for the rescue work in the view of approaching Cyclone Phailin. (PTI photo)

Three teams, each comprising 18 members, reached Visakhapatnam, while two military teams of 50 members each arrived in Visakhapatnam and 1 team each in Vizianagaram and Srikakulam.

Disagreement arose over the power packed by Phailin, although most forecasters expected it to weaken upon reaching the coast.

The Met department described it as a "very severe cyclonic storm" with wind speeds of 210-220 km per hour and resisted upgrading it to a stronger "super cyclone."

But the US Navy's Joint Typhoon Warning Centre predicted gusts of up to 315 kmph. London-based storm tracking service Tropical Storm Risk said Phailin was a super cyclone and placed it in the most intense Category 5 of powerful storms, evoking memories of the devastating 1999 storm when wind reaching speeds of 300 kmph winds battered Odisha for 30 hours.

Mohapatra agreed "Phailin will be no less than the 1999 super cyclone”.

An Odisha Met department bulletin said low lying areas of Ganjam, Khurda, Puri and Jagatsinghpur districts of Odisha will be inundated by a 15 feet high tide during the landfall.

Hover over the graphic for district-wise control room nos and helpline nos.Helplines

Odisha government on Friday set up control rooms to make available information related to rescue and other measures.

The helpline number of the Odisha Central Control Room is 0674-2534177, the sources said.

Important developments:

* The MeT department: DG LS Rathore said on Friday afternoon that Cyclone Phailin would hit coast between Kalingapatnam and Paradeep on Saturday evening and heavy rains were expected in Odisha, Andhra Pradesh, Jharkhand, Chhattisgarh, Bihar.

* The other regions which are expected to be affected by the cyclone include North Chhattisgarh, South Jharkhand, Eastern Uttar Pradesh, Bihar and gangetic West Bengal.

* Defence minister AK Antony directed the three services -- army, air force and the navy -- to prepare for meeting any challenge.

* Two IL-76 Indian Air Force aircraft have been dispatched this morning with National Disaster Response Force teams and equipment to Bhubaneshwar.

* A total of 24 aircraft including transport planes such as IL-76, C-130J Super Hercules and the Antonov-32 besides 18 helicopters have been deployed by the IAF.

* Authorities also planned to shift thousands of people and cattle to safer areas in neighboring Andhra Pradesh state, the state government statement said.

* Schools and colleges in Vishakhapatnam are closed; associations are moving around the district and advising people to prepare for the cyclone.

* The Vishakhapatnam-based Eastern Naval Command has kept multiple Indian Navy diving teams with inflatable rafts in standby mode at important locations which could be put into operations at short notices.

* People in affected districts and Bhubaneswar went for panic buying of essential items. Dry foods, candles, match boxes, soaps went off the shelves of shops, while potatoes and other vegetables disappeared from the markets. Long queues were seen in petrol pumps as people wanted to stock petrol and diesel for at least seven days.

A satellite image of cyclonic storm 'Phailin'. (The weather Channel)

* The government has cancelled Durga puja leaves of employees in all 30 districts.

“We want no casualties,” Odisha revenue minister SN Patro said. He said the government started evacuating people before the cyclone hits and will begin reopening roads and communication network by clearing uprooted trees after the cyclone subsides.

* Two important tourist destinations of Gopalpur and Puri in Odisha saw visitors leaving in droves because of fear of Cyclone Phailin striking tomorrow. All hotels, particularly those near the sea, at Puri were being vacated with tourists moved to safer places, official sources said.

* Paradip Port stopped cargo operations on Friday, port chairman Sudhanshu Shekhara Mishra. He said all vessels were ordered to leave the port, which handles coal, crude oil and iron ore. An oil tanker holding about 2 million barrels of oil, worth some $220 million, was among those moved, an oil company source said.

* Andhra Pradesh government put on alert all the coastal areas and readied rescue teams and monitoring mechanisms in north coastal districts of Srikakulam, Visakhapatnam, Vizianagaram, east and west Godavari districts.

Srikakulam bordering Odisha is most vulnerable and more than 64,000 people will have to be evacuated from Srikakulam, Vijianagaram and Visakhapatnam. Evacuation of people is yet to begin in Visakhapatnam and Vizianagaram.

In Srikakkulam district, 32 relief camps have been readied and 110 cyclone shelters identified. Buses of state road transport corporation and private operators too have been pressed into service. Some 287 villages have been advised to evacuate.

* At the Andhra ports of Krishnapatnam, Machilipatnam, Kalingapatnam, Bheemunipatnam, Visakhapatnam and Nizampatnam, authorities have raised the third-level danger flags. At Kalingapatnam, sea water reached up to the beach road.

* East Coast Railway plans to regulate and cancel about 24 passenger trains between Visakhapatnam and Bhadrak on the Howrah-Chennai Main Line route tommorow in view of the approaching cyclone.

The trains which will either be regulated or cancelled are Puri-Cuttack-Puri passenger, Paradeep-Cuttack passenger, Cuttack-Paradeep passenger, Puri-Gunupur-Puri passenger, Puri-Rourkela passenger, Puri-Cuttack passenger, Bhadrak-Cuttack-Bhadrak passenger and Cuttack-Palasa-Cuttack passenger trains, an ECoR official said.

* Andhra Pradesh breathed easy after nearly 30,000 electricity workers called off their strike on Friday in the wake of the cyclone, ending widespread power blackouts for millions of people.

* The government has already deployed the Odisha Disaster Rapid Action Force (ODRAF) and started mock drills in the districts most likely to be affected.

* On Thursday, Odisha chief minister Naveen Patnaik had cancelled his New Delhi visit and written to Union defence minister AK Antony for help in dealing with the impending calamity.